Donald Trump has been the subject of an "apparent assassination attempt" at his Florida golf club.
The Republican presidential nominee said he was "safe and well" after gunshots were heard in his vicinity while he was playing at his Trump International Golf Course in West Palm Beach just after 1.30pm local time on Sunday.
An official for the US Secret Service said agents opened fire after seeing a person with a firearm.
Election latest: Trump 'safe' after 'gunshots in his vicinity'
A suspect was later arrested and an AK-47 type assault rifle weapon and a scope, two backpacks and a GoPro device were recovered at the scene, Palm Beach County sheriff Ric Bradshaw said in a news conference.
What do we know so far?
Just after 7.30pm UK time, the Trump campaign released a statement to say Mr Trump was "safe following gunshots in his vicinity".
It is believed Mr Trump was taking part in a round at Trump International Golf Course in West Palm Beach at the time the shots were heard.
The FBI later confirmed it was investigating what "appears to be an attempted assassination of former president Trump".
Palm Beach County sheriff Mr Bradshaw said the gunman was about 400 to 500 yards away from Mr Trump and hidden in shrubbery while the former president played golf at a nearby hole.
He said the Secret Service agent - who was patrolling the course ahead of Mr Trump - spotted a rifle barrel coming out of a perimeter fence surrounding the course.
"He immediately engaged that individual, at which time the individual took off," Mr Bradshaw said.
Officials said it remains unclear whether the suspect fired first - or fired at all - or whether only the Secret Service fired.
Police 'surrounded vehicle' of suspect
A witness spotted the man fleeing the scene in a black Nissan SUV and managed to take photos of the car and number plate. Police then alerted the neighbouring Martin County Sheriff's Office which pulled over the vehicle and detained the suspect.
They are believed to be the same person who had a weapon outside the fences of the golf course.
Martin County Sheriff William Snyder told reporters his officers followed the suspect vehicle for a while before making a "felony stop".
"Our road units picked the vehicle up and we waited a while. We didn't stop him right away. We didn't want a high-speed chase," he said.
"So we were able to wait until we had adequate units, surrounded the vehicle, and forced it to a stop."
A witness said he saw "20 or more cop cars flying from nearby streets" as he described the emergency response outside Mr Trump's golf course.
"From what I saw, five black unmarked SUVs blocked in a grey Mercedes in front of the golf course," Max Egusquiza told the AP news agency.
"There were about 20 or more cop cars flying from nearby streets," he said.
Mr Trump was taken back to his Mar-a-Lago resort in Palm Beach after the scare.
What has Trump said?
Mr Trump later said in a fundraising email that he was safe.
"There were gunshots in my vicinity, but before rumours start spiralling out of control, I wanted you to hear this first: I AM SAFE AND WELL!" the email said.
"Nothing will slow me down. I will NEVER SURRENDER! I will always love you for supporting me.
"Unity. Peace. Make America Great Again. May God bless you."
Senator Lindsey Graham posted on X after speaking with him.
"He's in good spirits and he is more resolved than ever to save our country," Mr Graham, one of Mr Trump's top congressional allies, said.
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Has the White House responded?
Shortly after details of the "apparent attempted assassination" emerged, the White House said in a statement: "The President and Vice President have been briefed about the security incident at the Trump International Golf Course, where former President Trump was golfing.
"They are relieved to know that he is safe. They will be kept regularly updated by their team."
Kamala Harris, the vice president and Democratic presidential nominee, also said she was "glad" her rival for the presidency was safe after gunshots were heard "in his vicinity".
Writing on X, she said: "Violence has no place in America."